Description
Description: CNRM-GAME, Groupe d'étude de l'atmosphère météorologique, Joint Unit CNRS/Meteo-France (UMR3589), av. Coriolis, 31057 Toulouse, France. We evaluate the ISBACC land surface model over the
Amazon forest, and propose a revised parameterization of
photosynthesis, including new soil water stress and autotrophic
respiration functions. The revised version allows the model to
better capture the energy, water and carbon fluxes when compared to
five Amazonian fluxtowers. The performance of ISBACC is
slightly site-dependent but similar to the widely evaluated land
surface model ORCHIDEE, based on different assumptions. Changes made
to the autotrophic respiration functions, including a vertical
profile of leaf respiration, leads to simulate yearly carbon use
efficiency and carbon stocks consistent with an ecophysiological
meta analysis conducted on three Amazonian sites. Despite these
major improvements, ISBACC struggles to capture the apparent
seasonality of the carbon fluxes derived from the fluxtower
estimations. However, there is still no consensus on the seasonality
of carbon fluxes over the Amazon, stressing a need for more
observations as well as a better understanding of the main drivers
of autotrophic respiration.

Summary
Improving the ISBACC land surface model simulation of water and carbon fluxes and stocks over the Amazon forest